FIG. 1 illustrates a detail of an internal combustion engine known from DE 10 2010 016 037 A1 with an adjustable compression ratio in a portion of a connecting rod. Thus FIG. 1 illustrates a connecting rod 10 which includes a crank pin bearing eye 11 and a connecting rod bearing eye 12 wherein the crank pin bearing eye 11 connects the connecting rod 10 to a crank shaft that is not illustrated in FIG. 1 and the connecting rod bearing eye 12 connects the connecting rod 10 to a cylinder piston of an internal combustion engine that is not illustrated in FIG. 1. An eccentrical element adjustment device 13 is associated with the connecting rod 10 wherein the eccentrical element adjustment device includes an eccentrical element that is not shown in FIG. 1 and an eccentrical element lever 14 and eccentrical element rods 15, 16.
The eccentrical element lever 14 includes a bore hole that is arranged eccentrical relative to a center 17 of the connecting rod bearing eye 12 with a center 18, wherein the bore hole in the eccentrical element lever 14 receives the eccentrical element and a bore hole in the eccentrical element receives a piston pin. The eccentrical element adjustment device 13 is used for adjusting an effective connecting rod length leff, wherein a distance of the center 18 of the bore hole in that eccentrical element lever 14 from a center 19 of the crank pin bearing eye 11 is defined as connecting rod length. In order to rotate the eccentrical element 14 and thus to change the effective connecting rod length leff the eccentrical rods 15, 16 of the eccentrical element adjustment device 13 are moveable. A piston 20, 21 is associated with each eccentrical element rod 15, 16, wherein the pistons are respectively moveably supported in a hydraulic cavity 20, 23. A hydraulic pressure is provided in the hydraulic cavities 20, 23, wherein the hydraulic pressure impacts the pistons 20, 21 associated with the eccentrical element rods 15, 16, wherein moving the eccentrical element rods 15, 16 is possible or not possible as a function of an oil volume in the hydraulic cavities 22, 23.
The adjustment of the eccentrical element adjustment device 13 is initiated through impact of mass and load forces of the internal combustion engine which impact the eccentrical element adjustment device 13 during an operating cycle of the internal combustion engine. During an operating cycle the effective directions of forces impacting the eccentrical element adjustment device 13 change continuously. The adjustment movement is supported by the pistons 20, 21 that are loaded with hydraulic fluid and which impact the eccentrical element rods 15, 16, wherein the pistons 20, 21 prevent a reset of the eccentrical element adjustment device 13 based on various effective directions of the forces impacting the eccentrical element adjustment device 13.
The eccentrical element rods 15, 16 which interact with the pistons 20, 21 are connected on both sides with the eccentrical element 14. The hydraulic cavities 22 and 23 in which the pistons 20, 21 are supported are loadable with hydraulic oil through hydraulic oil conduits 24 and 25 from the crank pin bearing eye 11. Check valves 26 and 27 prevent a flow back of the hydraulic oil from the hydraulic cavities 23 and 24 back into the hydraulic conduits 24, 25. In a bore hole 28 of the connecting rod 10 a switch valve 29 is received whose function is already known from DE 10 2010 016 037 A1, wherein the switching position of the switch valve 29 determines which of the hydraulic cavities 22 and 23 is filled with hydraulic oil and which of the hydraulic cavities 22 and 23 is emptied, wherein this determines the adjustment direction or direction of rotation of the eccentrical element adjustment device. The hydraulic cavities 22 and 23 and thus are in contact with the bore hole 28 through fluid conduits 30 or 31 which are received by the switch valve 29. FIG. 1 schematically illustrates an actuation device 32, a spring device 33 and a control piston 34 of the switch valve 29, wherein the function of the components of the switch valve 29 is already known from DE 10 2010 016 037A1.
As stated supra the hydraulic oil which impacts the pistons 20, 21 supported in the hydraulic cavities 22, 23 is supplied to the hydraulic cavities 22, 23 starting from the crank pin bearing eye 11 through hydraulic conduits 24, 25, wherein the connecting rod 10 engages the crank pin bearing eye 11 at the crank shaft not illustrated in FIG. 1, so that a connecting rod bearing 35 shell is arranged between a crank shaft bearing pin of the crank shaft and the crank pin bearing eye.
DE 10 2005 055199 A1 illustrates further details of a combustion engine with adjustable compression ratio wherein it is known from this document to insert the eccentrical element lever, at which the eccentrical element rods engage, into a slot shaped recess in the connecting rod bearing eye. For mounting purposes the eccentrical element lever which includes a bore hole with inner teething is inserted into a slot shaped recess of the connecting rod bearing eye, wherein the eccentrical element which has external teething is subsequently inserted into the bore hole of the eccentrical element lever. The eccentrical element and the eccentrical element lever are connected with one another through teethings engaging one another. Connecting the eccentrical element with the eccentrical element lever through the teethings engaging one another causes a high level of production and assembly complexity and is therefore subject to wear.